1. Field of the Invention
This invention is in the field of medicinal chemistry. In particular, the invention relates to small molecules which function as inhibitors of anti-apoptotic Bcl-2 family member proteins (e.g., Bcl-2 and Bcl-xL). The invention also relates to the use of these compounds for inducing apoptotic cell death and sensitizing cells to the induction of apoptotic cell death. Field of the Invention
This invention is in the field of medicinal chemistry. In particular, the invention relates to small molecules which function as inhibitors of anti-apoptotic Bcl-2 family member proteins (e.g., Bcl-2 and Bcl-xL). The invention also relates to the use of these compounds for inducing apoptotic cell death and sensitizing cells to the induction of apoptotic cell death.
2. Related Art
The aggressive cancer cell phenotype is the result of a variety of genetic and epigenetic alterations leading to deregulation of intracellular signaling pathways (Ponder, Nature 411:336 (2001)). The commonality for all cancer cells, however, is their failure to execute an apoptotic program, and lack of appropriate apoptosis due to defects in the normal apoptosis machinery is a hallmark of cancer (Lowe et al., Carcinogenesis 21:485 (2000)). Most of the current cancer therapies, including chemotherapeutic agents, radiation, and immunotherapy, work by indirectly inducing apoptosis in cancer cells. The inability of cancer cells to execute an apoptotic program due to defects in the normal apoptotic machinery is thus often associated with an increase in resistance to chemotherapy, radiation, or immunotherapy-induced apoptosis. Primary or acquired resistance of human cancer of different origins to current treatment protocols due to apoptosis defects is a major problem in current cancer therapy (Lowe et al., Carcinogenesis 21:485 (2000); Nicholson, Nature 407:810 (2000)). Accordingly, current and future efforts towards designing and developing new molecular target-specific anticancer therapies to improve survival and quality of life of cancer patients must include strategies that specifically target cancer cell resistance to apoptosis. In this regard, targeting crucial negative regulators that play a central role in directly inhibiting apoptosis in cancer cells represents a highly promising therapeutic strategy for new anticancer drug design.
Two classes of central negative regulators of apoptosis have been identified. The first class of negative regulators of apoptosis is the inhibitor of apoptosis proteins (IAPs) (Deveraux et al., Genes Dev. 13:239 (1999); Salvesen et al., Nat. Rev. Mol. Cell. Biol. 3:401 (2002)). IAP proteins potently suppress apoptosis induced by a large variety of apoptotic stimuli, including chemotherapeutic agents, radiation, and immunotherapy in cancer cells.
The second class of central negative regulators is the Bcl-2 family of proteins, as exemplified by two potent anti-apoptotic molecules, Bcl-2 and Bcl-xL proteins (Adams et al., Science 281:1322 (1998); Reed, Adv. Pharmacol. 41:501 (1997); Reed et al., J. Cell. Biochem. 60:23 (1996)). The Bcl-2 family of proteins now includes both anti-apoptotic molecules such as Bcl-2 and Bcl-xL and pro-apoptotic molecules such as Bax, Bak, Bid, and Bad. Therapeutic strategies for targeting the anti-apoptotic Bcl-2 family members, such as Bcl-2 and Bcl-xL, in cancer to restore cancer cell sensitivity and overcome resistance of cancer cells to apoptosis have been extensively reviewed (Adams et al., Science 281:1322 (1998); Reed, Adv. Pharmacol. 41:501 (1997); Reed et al., J. Cell. Biochem. 60:23 (1996)). Currently, Bcl-2 antisense therapy is in several Phase III clinical trials for the treatment of solid and non-solid tumors. Several laboratories are interested in designing small molecule inhibitors of Bcl-2 and Bcl-xL.